If you don't intend transmitting near the antenna, Tr3 and it's associated components could be omitted.
The MMBT3904 is the surface mount version of a 2N3904, D1 (Schottky diode) could be replaced with a 1N4001. The design is not critical and there is no need to use surface mount, use whatever parts are available. My version of the active antenna is built using mostly surface mount parts, the diagram is here. The feedline choke and the DC injection circuit must be mounted in plastic boxes to provide isolation between the input and output coax sockets. 12 turns of coax through an FT240-31 should keep most of the noise from the house away from the antenna. The feeder has to be grounded to an earth rod near the antenna, add a feedline choke in the coax run on the shack side of this earth rod. The original PA0RDT antenna articles are widely available on the web. In addition there are back to back diodes and a series protection lamp, plus a transmit switching transistor to remove the supply while transmitting. This particular version of the PA0RDT antenna uses slightly "stiffer" bias on the 2N5109 base and more effective isolation of mains borne QRM at the DC injection (bias Tee) end. The patch antenna has had an additional piece of wire added in the form of a hair pin, nothing special, just a length of wire soldered to the print board patch. Mine is installed in an 18 inch long piece of plastic waste water pipe at only 7 feet above ground. The PA0RDT uses the outer of the feeder as one half of the antenna, you can add more "patch" and less "height" for more or less the same result. The original PA0RDT antenna uses a very small patch for the antenna and relies on the antenna being installed quite high. The cable from the power-feed unit to the radio must also be supplied by the user.Ĭopyright 2013-2022, Universal Radio, Inc.Active antennas can be very useful, in particular they can help reduce local electrical noise by allowing the antenna to be installed in a corner of the garden well away from house wiring.
Additionally, the user must supply the BNC male to BNC male cable between the power-feed unit and the Mini-Whip antenna element. Please note that is antenna system only includes the two components shown above. This antenna operates from 12 to 15 VDC 65mA. Power is fed to the Mini-Whip via the coaxial feed line. The compact size lends itself to portable operation, mobile and maritime installations as well for outdoor base use with restricted covenants. The Bonito Mini-Whip© antenna receives from 10 kHz to 30 MHz with impressive performance.
Bonito Mini Whip Antenna, Bonito Mini-Whip Antenna PA0RDT
0 kommentar(er)
